Self-cleaning oven with door lock light

ABSTRACT

A heat-cleaning oven circuit is disclosed having a door lock thermostat which opens above a predetermined minimum temperature such as 550* to ensure that the latching assembly for the oven cannot be unlocked until the temperature within the oven has again dropped below 600*. A door lock indicating light is provided connected directly across the normally closed contacts of the door lock thermostat so the door lock thermostat shorts out the door lock indicating light at all temperatures below door-locking temperatures, while the door lock light provides a positive indication when the locking assembly is in an unlockable condition and the contacts of the door lock thermostat are open. Nuisance lighting during operation other than heat cleaning is prevented by a circuit arrangement which connects opposite sides of the light to neutral.

United States Patent [72] Inventor Calvin .Llloltkamp 3,412,236 11/1968 l-lild etal. 219/413 Mansfield, Ohio 3,484,858 12/1969 Jordan et al. 219/413 [21] Appl. No. 45,098 3,549,862 12/1970 Holtkamp et a1. 219/519 523 firs Primary Examiner-Harold Broome Assignee wesfinghousemecmc Corporafion Attorneys F. H. Henson, E. C. Arenz and R. B. Farley Pittsburgh, Pa.

ABSTRACT: A heat-cleaning oven circuit is disclosed having a door lock thermostat which opens above a predetermined [54] SELRCLEANING OVEN WITH DOOR LOCK minimum temperature such as 550 to ensure that the latching LIGHT assembly for the oven cannot be unlocked until the tempera- 8 Claims 2 Drawing Figs ture within the oven has again dropped below 600. A door lock indicating light is provided connected directly across the 219/l3 normally closed contacts of the door lock thermostat so the Cl Azlb door lock thermostat shorts out the door lock indicating light [50] Field of Search 219/410, 3! a" temperatures below dooHocking temperatures while 411,412,413,393,398, 51 the door lock light provides a positive indication when the R t d locking assembly is in an unlockable condition and the con- [56] e erences I e tacts of the door lock thermostat are open. Nuisance lighting UNITED STATES PATENTS during operation other than heat cleaning is prevented by a 3,270,183 8/1966 Jordan 219/398 circuit arrangement which connects opposite sides of the light 3,353,004 1 H1967 Alexander 219/413 to neutral.

94 9 'vAvA'A AVA 84 9a r L3 A? NTT m H fi 28 52 re :5; l 54 3O 78 x p 58 i3! 60 x'T'o i-" /56 as To 61 11 62 s a t s w as w- 4'6 l J PROBE -j- INDICATOR [4a -l2 52 1 is 14 '0 "2'4 SELF-CLEANING OVEN WITIIDOOR LOCK LIGHT BACKGROUND OF THE. INVENTION 1. Field of the Invention This invention relates'to oven systems and, more particularly, relates to a heat-cleaning oven circuit which includes a positive door indicating light.

2. Description of the Prior Art The use of a door lock indicating light is not new in the oven circuit art, with the same being shown, for example, in U.S. Pat. No. 3,] 16,398-issued Dec. 31, I963. However, the use of such an indicating light in an oven circuit that controls the cleaning operation through a single temperature peak has heretofore generally required the use of a substantially highpriced arrangement to provide a functioning door lock indicating light. Various switching arrangements have been devised in the past in a single peak circuit to provide a door lock indicatinglight but ineach case the-cost of the lock indicating light featuresoutweighed the somewhat minor (by comparison) advantages over a single peak circuit without such a feature.

Accordingly, while the invention is useful in systems other than a single peak control system, it will be described mainly in connection therewith.

SUMMARY OF THE INVENTION In accordance with the principles of the invention, a heatcleaning oven system is provided that includes an oven door latching arrangement, a thermostatic switch for preventing operation of the latching means in an unlatching direction in response to oven temperatures above normal oven cooking temperatures. i I

To this generally conventional arrangement, as shown, for example, in U.S. Pat. application Ser. No. 773,539, filed on Nov. 5, I968 and now U.S. Pat. No. 3,549,862, and owned by a common assignee, a door lock light is placed in parallel with the thermostatic switch and a circuit means is added'connecting the light between neutral and an artificial neutral when the oven is set for certain cooking operations which might effect opening of the switch and which removes the artificial neutral when the oven is set for heat cleaning so that the light can be energized during the appropriate time. This is preferably accomplished by connecting one side of the door lock light to the neutral side of the power supply for the oven circuit while the other side of the door lock light is connected to the center point of two voltage-dividing resistors which are connected in series between the L, side of the power supply and a terminal of the selector switch that places the oven circuitry in its various modes of operation. During the baking and broiling operations, this terminal of the selector switch means is connected to the L, side of the power supply which places the full 236 volts across the two resistors, thus making the center point to which one side of the door lock indicating light is connected an artificial neutral. With this arrangement for the door lock light, even if the oven cavity becomes hot enough to open the door lock thermostat, the door lock indicating light cannot be energized because both sides of it are connected to neutral potential.

During the cleaning operation, the selector switch contact is opened to the L, supply side of the electrical potential so that the artificial neutral is removed. A circuit is thereby completed through one of the resistors and the door lock indicating light (with the door lock thermostat open) to the neutral side of the power supply thereby energizing the light so that it indicates that-the oven is in the clean mode at a temperature which prevents operation of the door latch from its locked condition.

DRAWING DESCRIPTION For a better understanding of the invention, reference may be had to the preferred embodiment, exemplary of the invention, shown in the accompany drawings in which:

FIG. I is a partly diagrammatic and schematic view of the electric circuit arrangement according to the invention; and

FIG..2 is a tablewhich identifies those contacts of the selector switch means that are closed for particular settings of the selector switch means.

PREFERRED EMBODIMENT OF THE INVENTION In FIG. 1 the oven cavity for an oven circuit means 11 is generally indicated by the dash-dot line rectangle 10. Only those parts which are physically located in the cavity which are necessary for the heating will now be described as included therein. The oven means includes a broil heater 12, a bake heater l4 and an auxiliary broil heater 16 which is used in conjunction with the regularbroil heater 12 to obtain simultaneous broiling of the opposite faces of a food article. The oven broil heater 12 is also utilized as the heating element for the oven circuitry during the clean mode of operation.

An oven selector switch means 18, schematically indicated by a dash-rectangle, includes a plurality of fixed and movable contacts'by which connections are made to energize various circuits of the oven circuit 11. A series of 14 external terminalsare provided for the selector switch means 18, with these external terminals indicated by letter reference in FIG. I

which correspond to the letter references given across the top of the table of FIG. 2. The X designation in any of the columns of the Table of FIG. 2 indicates that those contacts in that column are in electrical current-carrying capacity for that particular mode of operation of the oven. I

A temperature controller 20 of a general bridge character is provided for the oven circuit 11, with this temperature controller including an auxiliary relay 22 in one of its legs which actuates relay switch means 24 and 26. Upon a sufi'rcient difference in potential across the temperature sensor 20 and thereby a flow of current in auxiliary relay 22 there is a con sequent generation of heat in it to move the aforementioned relay switch means 24 and 26 to closed position. Temperature controller 20, as will be explained later, controls the temperature within the oven for all heating modes of oven save for the cleaning mode.

A latching arrangement 28 to ensure that latching of the oven door (not shown) occurs prior to the heat-cleaning cycle being initiated is shown fragmentarily. The mechanism by which latching occurs and places the oven circuit ll in a condition for locking is of the same general character as the latching arrangement disclosed in U.S. Pat. No. 3,387,874 issued on June ll, I968, and ownedby a common assignee. Reference may now be had to teat patent for a fuller understanding of the operation of the locking and latch assembly of the oven utilizing the oven circuit 1 l. Essentially, the latch assembly includes (schematically shown) a pivoted latching element 30 which is pivotally movable during actuation of the latch assembly to locked condition in thedirection indicated by the arrow and a solenoid 32 that actuates a locking pin 34 in an upward direction away from the pivoting latch element 30. Upon placing the selector switch means 18 in the latch mode, the solenoid 32 is energized drawing the locking pin 34 upwardly. Mechanical manipulation of the latching arrangement then moves the pivoted latch element 30 in the direction of the arrow. Movement of the selector switch means 18 to the clean mode, at this time, causes the solenoid 32 to be disengaged and the locking pin 34 to drop downwardly behind the pivoting latch element 30 preventing its swinging return which is required for unlatching so that the oven door (not shown) is effectively locked in the heat-cleaning mode.

For a fuller understanding of the operation of some of the other elements of the oven circuit 11 reference should be made to the following U.S. Pat. applications: Kastovich, application Ser. No. 552,663 and now U.S. Pat. No. 3,504,l6l relating to the manner in which heat is applied to the oven for a high-temperature quick-cleaning cycle and I-Ioltkamp. U.S. Pat. No. 3,440,402, relating to the pulsing of the oven heating means and both owned by a common assignee.

The source of electrical power for the oven control system 11 is a conventional source, comprising a tree-line system in which a nominal 240 volt alternating current potential exists between power connections denoted L and L and with 120 volts alternating current potential existing between either hot lines and a neutral designated N.

The temperature controller 20, described above, may be of the general type described in US. Pat. 2,962,575 issued Nov. 29, 1960 and owned by a common assignee, with it operating during cooking to energize and deenergize the auxiliary relay 22 in accordance with whether the sensed temperature in the oven is above or below the temperature to which the temperature controller has been set. The relay switch means 24 and 26, of course, close whenever the hot wire actuating means 36 of the relay 22 is energized. After deenergization, the hot wire 36 gradually cools and after a slight moment in time the relay switch means 24 and 26 open. This delay provides time for a holding circuit to be established when the relay switch means 24 and 26 are closed.

The temperature controller 20 is connected in a temperature controller circuit 38 which includes a secondary 40 of a transformer 42. A temperature controller bypass circuit 44 is also provided which includes a pair of leads 46 and 48 leading to the terminals A and H of the selector switch means 18. This bypass circuit means is inoperative in the cooking mode for the oven circuit 11 since the terminals A and H are not in a currentqcarrying condition. During cooking operation, the temperature controller 20 is energized by the aforementioned temperature controller circuit 38 that includes a pair of leads 50 and 52 connected to the secondary of the transformer 42 and to the temperature controller 20. Temperature controller circuit 38 is thereby formed with a closed loop and normally operated at a very low voltage such as 11 volts for example, although this circuit may be operated at a higher voltage if required merely by altering the number of turns in a primary and secondary of the transformer 42.

An energizing circuit 53 for the transformer 48 and, accordingly, for the temperature controller 38, includes a transformer primary 54 connected to neutral through a lead 56 and a lead 58 extending to one side of a clean thermostat switch 60 which, by opening, when a preset predetermined temperature (say l,050) has been reached, terminates the cleaning cycle.

The opposite side of the clean thermostat 60 is electrically connected to a lead 62 which extends to an interlock switch 64 that is moved between two positions by the lock pin 34. More specifically, the interlock switch 64 assumes the full line position illustrated when the latching assembly 28 is in an unlatched position and moves to the dotted line position shown in FIG. 1 when the locking pin 34 engages behind the pivoting latch element 30, this locking pin abutting the interlock switch during this movement to thereby physically move the interlock switch 64 to the dotted line position. In its upper position, interlock switch 64 is in electrical contact with a lead 66 which extends to the terminal X of a first switch 67 of selector switch 18 and in its lower, dotted line position, interlock switch 64 is in electrical connection with a lead 68 which extends to an ambient thermostat 70 that opens in the event the ambient temperature outside the oven assumes an upper limit which makes continued operation of the oven unsafe. This thermostat can be set, for example, at 200 F. The opposite side of the ambient thermostat 70 is electrically connected to a lead 72 which extends to the electrical supply on the L,'side of the circuitry. The energizing circuit 53, then, is comprised of the primary S4 of the transformer 40, the lead 58, clean thermostat 70, interlock switch 64 and lead 66 extending to terminal X and the first switch 67. The holding branch comprises the lead 72 extending from the L side of the current supply, ambient thermostat 70, interlock switch 64, clean thermostat 60, lead 58 and primary 54 of the transformer 40.

In a normal baking operation, the temperature controller 20 is energized through the energizing branch including the primary 54 of a transformer 40 which provides a low voltage to the upper and lower corners of the bridge arrangement for the temperature sensor 20 so that energization of the hot-wire relay element 36 is in accordance with the difference between the oven temperature and the temperature sensing of the bridge. For heat-cleaning operation, the temperature controller 20 is bypassed or disabled by closure of a second switch 74 which places the A and H terminals in a current-carrying condition in the selector switch means 18 to complete the temperature control bypass circuitry 44 that includes the leads 46 and 48 and the second switch 74. This action shorts out the side of the bridge which includes the internal switch which normally opens and closes in accordance with the differential between the sensed temperature of the temperature controller 20 and the oven temperature. Thus, a low voltage is applied directly across the thermal relay elements 36 so that the relay switch means 24 and 26 are maintained in a closed currentcarrying condition.

in order to actuate the solenoid 32 during the latching operation of the oven, a third switch 76, in the selector switch means 18, has a closed position in the latch mode of operation in which terminals C and L, are placed in a current-carrying condition. This provides a flow of current to the solenoid 32 since a circuit is completed from the power supply side L, to neutral N, through the third switch 76, a lead 78 attached to the C terminal, the solenoid 32 and a lead 80 extending from the opposite side of the solenoid 32 and electrically connected to a door lock thermostat 82. A lead 84 extends to neutral N from this door lock thermostat. The door lock thermostat 82 serves as a blocking switch to prevent reactivation of a solenoid 32 once a temperature above normal cooking temperature, say 650 F has been reached. At this time, the door lock thermostat 82 opens and further closing of the third switch 76 to place L and C terminals in a current carrying condition does not provide a completely closed circuit through the solenoid 32.

A fourth switch 86 of the selector switch means 18 is closed only in the clean mode and connects the L terminal to the S terminal to connect the L, side of the electrical supply source to the L, side of the electric supply through a lead 88 which extends to and is in electrical connection with the broil element 12. A pulse switch 90 is also disposed in this circuit arrang'ement so as to provide a pulsing current flow through the broil element 12 in order to prevent its actuation at all times during the heat-cleaning cycle and to thereby provide a pulsing energy flow to it.

The manner in which the oven is operated to carry out a heat-cleaning cycle is as follows. Assume the oven door (not shown) is closed but not latched. The selector switch means 18 is turned from an off position to a latch position. This closes the first, second and third switches 67, 74 and 76 of the selector switch means 18 and places, through the closure of switch 67, the energizing branch of the energizing circuit 57 in a current-carrying condition to energize the primary 54 of the transformer 40. Closure of the second switch 74 also affords energization to the temperature control bypass circuit 44 so that the voltage applied to the hot wire relay element 36 causes the relay switch means 24 and 26 to close and remain closed independent of the temperature controller 20. The relay switch means 26 is in circuit with the broil element 12 but this element is not yet actuated since the fourth switch 86 has not yet been closed. Closure of the relay switch means 24, however, does complete a portion of a holding circuit for the temperature sensor 20. This circuit will be completed when the interlock switch 64 has been moved to its lower dotted line position, upon completion of the latching of the latching assembly 28 for the oven.

in the embodiment illustrated, the solenoid 32 emits a buzzing noise which indicates to the user of the oven that the latch means may now be manipulated to a latched position. In so doing, the pivoting latch element 30 swings out of the way of the solenoid locking pin 34 so that when the solenoid is subsequently deenergized the locking pin 34 can drop and thereby move interlock switch 64 to its lower dotted position. The aforementioned movement of the solenoid takes place after the latching of the door and when the user turns the selector switch means 18 from a latch to a clean position. The terminals across the third switch means 76 open, at this time,

disabling energization to'the solenoid 32 so that the locking pin is free to move to its lower position. At this same time, the second switch 74 closes to control the bypass circuit and the fourth switch 86 of the selector switch means 18 is closed to complete the broil element heater circuit. Thus, after the selector switch means 18 has'been operatedto a clean position, the primary 54 of thetransformer 42 remains energized through the holding branch of the energizatng circuit. The temperature controller circuit 38 is energized from the secondary 40 of the transformer and the temperature sensor 30 is shorted out by the bypass circuit so that the switches 24 and 26 remain closed independent of the temperature reached in the oven cavity. As a result, the oven temperaturecontinues to increase through energization of the broil heater element 12 through energization of the broil/heater element .12 through thepulse switch 90.

As the oven temperature rises above the normal cooking temperature, door lock thermostat 82 opens to prevent energization of the solenoid 32 through operation of the selector switch means 18 from a clean to alatch position. This thermostat remains open until the temperature in the oven cavity again assumes the normal cooking temperature. Upon attaining the maximum heat-cleaning temperature set on the clean thermostat 60, this normally closed thermostatopens thereby removing current from the primary 54 of transformer 42. The loss of power through temperature controller circuit and the temperature controller bypass circuit results in-deenergization of the relay switch means 24 and 26 so that these switches will open after a short delay for cooling of the hot wire 36. Opening of relay switch means 26 results in adeenergization of the broil element 12, while opening of relay switch means 24 prevents reenergization of the temperature controller circuit through the temperature controller 20. The clean thermostat 60 again closes when a lower temperature is reached by the oven cavity. At the time when the temperature in the oven cavity has reached the normal cooking range, the door lock thermostat 82 again closes which permits operation of the latching assembly 28 to an unlocked condition so that the oven door (not shown) may be opened and the remaining residue contained in the oven cavity may be wiped from its interior periphery by use of. a dry cleaning cloth. The oven circuit means 11 is now again ready to be placed in any of the desired cooking or cleaning modes.

The cleaning mode may be terminated at any time after it has started by turning the selector switch means 18 from a clean position to a latch position if the oven has not yet assumed a temperature above that which actuates the door lock thermostat 82 to an open condition. The solenoid 32 will be energized and a loud buzzing sound will indicate to the user of the oven that the latching assembly 28 may be moved to an unlocked condition. If the temperature in the oven cavity has risen above that temperature at which the door lock thermostat 82 opens, setting of the selector switch 18 to the latch position will not result in the solenoid again being energized. However, this action does deenergize the broil element 12 so that once the temperature is reached where the door lock thermostat 82 again closes, the latching assembly 28 may again be actuated to an unlocked condition.

The men circuit 11 so far related is generally shown and described in US. Patent Application 773,539 filed Nov. 5, I968 and now U.S. Pat. No. 3,549,862, and owned by a common assignee. The improvement to this circuit arrangement includes the provision of a door lock light 92 which indicates that time period during the cleaning cycle when the latching assembly 28 cannot be manipulate to an unlatched position.

Door lock light 92 is situated in a door lock and light circuit 94 that includes a pair of leads 96 and 98. Lead 96 is connected to one side of the lock switch and to neutral throughlead 84, and lead 98 is connected to the other side of the switch. Thus, the door lock light 92 is placed directly across the door lock thermostat 82, so that the door lock thermostat, when closed, shorts out the light and thereby eliminates actuation of the indicating light at all temperatures below door locking temperatures. A lead extends from electrical connection with the lead 98 to a center point 103 between two voltage dividing resistors 102 and 104 that are connected in series between terminal X of the selector switch and theL, side of the power supply.

During baking and broiling operation, the contacts L, and X are closed since the-first switch 67 isclosed and thus the terminal X is at the L, potential. This places 240 volts across the two resistors, making the center point 103 to which lead 100 is connected an artificial neutral. Thereby, door lock indicating light 92 cannot be energized. However, during the cleaning operation, selector switch contacts L, and X are open so that no potential is received from the L side of the supply arrangement to the resistor 104 and-the potential at junction 103 is no longer at neutral N. A volt circuit is thereby completed through theresistor 102 and the door lock light 92 from L, to neutral. The door lock light 92 then operates as a true lock light indicating that the door lock thermostat 82 is open and the oven is in a cleaning mode with the temperature above the normal cooking range and with the latching-arrangement in a nonunlocking condition.

.It should be clear to those skilled in the art that a door lock light feature has been provided for a cleaning oven system which is inexpensive to include in such a system and yet satisfies all the requirements of a true indicating light for doorlocking conditions. It should also be clear to one skilled in the art that other obvious arrangements within the purview of this invention couldbe utilized to provide a door lock light for an oven-cleaning circuit.

What is claimed is:

1. An oven circuit having cooking and self-cleaning cycles including:

a. heating element means,

b. selector switch means for energizing at least one of said heating element means,

c. an electrical energy three-line source including a neutral,

an L, side and an L, side, door lock thermostat means in a series relationship with said neutral source, e. door lock light indicating means connected in parallel with said door lock thermostat means, f. an artificial neutral adapted to be formed between two relatively high resistances, g. one of said resistances being connected to said L, side of said electrical energy source, and the other of said resistances being connectable to said L side of said electrical energy source through said selector switch means when in a cooking position, and said door lock light indicating means connected between said neutral and artificial neutral.

2. The combination set out in claim 1 wherein:

a. said selecto switch means includes a switch connectable between the L, side of said electrical energy source and its respective resistance,

b. said switch is opened in said self-cleaning cycle position of said selector switch.

3. The combination set out in claim 2 wherein:

a. said door lock thermostat means opens to effect energization of said door lock light, when said switch is in said self-cleaning cycle.

4. In a pyrolytic heat-cleaning oven including a selector switch selectively settable for a heat-cleaning operation, and for cooking operations capable of heating the oven to temperatures at which the door of said oven is to be locked, at circuit arrangement for eliminating nuisance lighting of an oven door lock light, comprising:

a three-wire electrical supply including a neutral, one side,

and the other side of the line;

a lock light;

normally closed switch means in parallel with said lock light for shunting said lock light when said oven is below a temperature at which said door is to be locked;

circuit means connecting one side of said light and said normally closed switch means to neutral, and the other side to a circuit location between said one side of the line and said selector switch;

circuit means connecting said selector switchto the said other side of the line;

said selector switch, when set to a cooking operation capable of elevating the oven to a locking temperature, imposing an electrical neutral upon said circuit location, and

when set to a heat-cleaning operation disconnecting said circuit location from said other side of said line; so that said light is effectively between neutral when said selector switch is set for those higher temperature cooking operations, and is between neutral and said one sideof the line when said selector switch is set for a heatcleaning operation.

5. The combination set out in claim 4 wherein:

a high-value resistance is disposed between said circuit location and said one side of the line, and

a high-value resistance is disposed between said circuit location and said other side of said line.

6. The combination set out in claim 4 wherein:

said normally closed switch is open when said oven is at a temperature when said door of said oven is locked.

7. In a pyrolytic heat-cleaning oven including a selector switch selectively settable for a heat-cleaning operation, and for cooking operations capable of heating the oven to temperatures at which the door of said oven is to be locked, a circuit arrangement for eliminating nuisance lighting of an oven door lock light comprising:

a light and lock circuit including said lock light, and a normally closed thermostatic switch operable to an open position in response to oven temperatures at which said door is to be locked, said thermostatic switch being in parallel with said light in said circuit to shunt said light and prevent its energization while said switch is closed;

a three-wire electrical supply including a neutral, and one side, and the other side of the line;

voltage divider means;

circuit means connecting one side of said voltage divider means to said one side of said line, and the other side of said voltage divider means to said other side of said line through said selector switch means when said selector switch is set for those higher temperature cooking operations capable of heating said oven to temperatures effecting said opening of said thermostatic switch, said other side of said voltage divider means being disconnected from said other side of said line when said selector switch means is set for heating cleaning operation;

said lock and light circuit having one side connected to said neutral, and the other side connected to the approximate electrical center of said voltage divider means so that said lock and light circuit is effectively between neutral when said selector switch is set for those higher temperature cooking operations, and is between neutral and said one side of the line when said selector switch is set for a heatcleaning operation.

8. The combination set out in claim 7 wherein:

said voltage divider means includes a relatively high-value impedance means. 

1. An oven circuit having cooking and self-cleaning cycles including: a. heating element means, b. selector switch means for energizing at least one of said heating element means, c. an electrical energy three-line source including a neutral, an L1 side and an L2 side, d. door lock thermostat means in a series relationship with said neutral source, e. door lock light indicating means connected in parallel with said door lock thermostat means, f. an artificial neutral adapted to be formed between two relatively high resistances, g. one of said resistances being connected to said L1 side of said electrical energy source, and the other of said resistances being connectable to said L2 side of said electrical energy source through said selector switch means when in a cooking position, and h. said door lock light indicating means connected between said neutral and artificial neutral.
 2. The combination set out in claim 1 wherein: a. said selector switch means includes a switch connectable between the L2 side of said electrical energy source and its respective resistance, b. said switch is opened in said self-cleaning cycle position of said selector switch.
 3. The combination set out in claim 2 wherein: a. said door lock thermostat means opens to effect energization of said door lock light, when said switch is in said self-cleaning cycle.
 4. In a pyrolytic heat-cleaning oven including a selector switch selectively settable for a heat-cleaning operation, and for cooking operations capable of heating the oven to temperatures at which the door of said oven is to be locked, a circuit arrangement for eliminating nuisance lighting of an oven door lock light, comprising: a three-wire electrical supply including a neutral, one side, and the other side of the line; a lock light; normally closed switch means in parallel with said lock light for shunting said lock light when said oven is below a temperature at which said door is to be locked; circuit means connecting one side of said light and said normally closed switch means to neutral, and the other side to a circuit location between said one side of the line and said selector switch; circuit means connecting said selector switch to the said other side of the line; said selector switch, when set to a cooking operation capable of elevating the oven to a locking temperature, imposing an electrical neutral upon said circuit location, and when set to a heat-cleaning operation disconnecting said circuit location from said other side of said line; so that said light is effectively between neutral when said selector switch is set for those higher temperature cooking operations, and is between neutral and said one side of the line when said selector switch is set for a heat-cleaning operation.
 5. The combination set out in claim 4 wherein: a high-value resistance is disposed between said circuit location and said one side of the line, and a high-value resistance is disposed between said circuit location and said other side of said line.
 6. The combination set out in claim 4 wherein: said normally closed switch is open when said oven is at a temperature when said door of said oven is locked.
 7. In a pyrolytic heat-cleaning oven inCluding a selector switch selectively settable for a heat-cleaning operation, and for cooking operations capable of heating the oven to temperatures at which the door of said oven is to be locked, a circuit arrangement for eliminating nuisance lighting of an oven door lock light comprising: a light and lock circuit including said lock light, and a normally closed thermostatic switch operable to an open position in response to oven temperatures at which said door is to be locked, said thermostatic switch being in parallel with said light in said circuit to shunt said light and prevent its energization while said switch is closed; a three-wire electrical supply including a neutral, and one side, and the other side of the line; voltage divider means; circuit means connecting one side of said voltage divider means to said one side of said line, and the other side of said voltage divider means to said other side of said line through said selector switch means when said selector switch is set for those higher temperature cooking operations capable of heating said oven to temperatures effecting said opening of said thermostatic switch, said other side of said voltage divider means being disconnected from said other side of said line when said selector switch means is set for heating cleaning operation; said lock and light circuit having one side connected to said neutral, and the other side connected to the approximate electrical center of said voltage divider means so that said lock and light circuit is effectively between neutral when said selector switch is set for those higher temperature cooking operations, and is between neutral and said one side of the line when said selector switch is set for a heat-cleaning operation.
 8. The combination set out in claim 7 wherein: said voltage divider means includes a relatively high-value impedance means. 